All Your Products Are Oil-Free and Matte
You might have started using oil-free and mattifying products in your teens, when your skin could not take any extra oil. If you've never reassessed your products, you might still be using oil-absorbing products. Matte-finish foundations and makeup contribute to making skin appear dry, so switch to something with a radiant finish.
If you are nervous to change all your products, keep your oil-free primers or setting products and switch to a light foundation that is water-based. When looking at labels, the first main ingredient should be water. My favorite is the Nars Sheer Glow Foundation ($47). This product will even out skin tone and hydrate it, leaving behind a gorgeous natural glow.